Group III nitride based quantum well light emitting device structures with an indium containing capping structure

Abstract

Group III nitride based light emitting devices and methods of fabricating Group III nitride based light emitting devices are provided. The emitting devices include an n-type Group III nitride layer, a Group III nitride based active region on the n-type Group III nitride layer and comprising at least one quantum well structure, a Group III nitride layer including indium on the active region, a p-type Group III nitride layer including aluminum on the Group III nitride layer including indium, a first contact on the n-type Group III nitride layer and a second contact on the p-type Group III nitride layer. The Group III nitride layer including indium may also include aluminum.

1. A Group III nitride based light emitting diode, comprising:
 an n-type Group III nitride layer; 
 a Group III nitride based light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 an undoped Group III nitride capping layer comprising indium on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the undoped Group III nitride capping layer comprises a plurality of undoped InAlGaN sublayers, and wherein the undoped Group III nitride capping layer is directly on a GaN layer; and 
 a p-type Group III nitride layer including aluminum directly on the undoped Group III nitride capping layer and remote from the Group III nitride based light emitting diode active region. 
 
     
     
       2. The light emitting diode of  claim 1 , wherein the undoped Group III nitride capping layer comprising indium is from about 20 Angstroms (Å) to about 320 Å thick. 
     
     
       3. The light emitting diode of  claim 1 , further comprising:
 a second contact on the p-type Group III nitride layer including aluminum; and 
 a p-type Group III nitride layer disposed between the second contact and the p-type Group III nitride layer including aluminum. 
 
     
     
       4. The light emitting diode of  claim 1 , wherein the p-type Group III nitride layer including aluminum also includes indium. 
     
     
       5. The light emitting diode of  claim 1 , wherein the Group III nitride capping layer comprising indium is configured to increase a brightness of light output from the light emitting diode by at least about 15% as compared to a capping layer that does not include indium. 
     
     
       6. The light emitting diode of  claim 1 , wherein the GaN layer comprises an undoped GaN layer between the light emitting diode active region and the Group III nitride capping layer. 
     
     
       7. The light emitting diode of  claim 1 , wherein the GaN layer comprises a barrier layer of the quantum well structure. 
     
     
       8. The light emitting diode of  claim 1 , further comprising:
 a plurality of AlGaN sublayers on the Group III nitride capping layer. 
 
     
     
       9. The light emitting diode of  claim 8 , wherein ones of the plurality of AlGaN sublayers comprise doped sublayers. 
     
     
       10. The light emitting diode of  claim 8 , wherein sublayers distal from the active region comprise higher Al compositions than sublayers proximate the active region. 
     
     
       11. The light emitting diode of  claim 10 , wherein the Al compositions of the sublayers are graded in a stepwise fashion from sublayers distal from the active region to sublayers proximate the active region. 
     
     
       12. The light emitting diode of  claim 10 , wherein the sublayers comprise Al compositions that continuously decrease from sublayers distal from the active region to sublayers proximate the active region. 
     
     
       13. The light emitting diode of  claim 1 , wherein an Al composition of the p-type Group III nitride layer is less than that of one of the plurality of InAlGaN sublayers directly thereon. 
     
     
       14. The light emitting diode of  claim 1 , wherein the Group III nitride capping layer comprising indium comprises a substantially uniform composition throughout the capping layer. 
     
     
       15. The light emitting diode of  claim 1 , wherein the light emitting diode comprises a vertical orientation. 
     
     
       16. A Group III nitride based light emitting diode, comprising:
 an n-type Group III nitride layer; 
 a Group III nitride based light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 an undoped Group III nitride capping layer comprising indium on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the undoped Group III nitride capping layer comprises a first sublayer of In x Al y Ga 1-x-y N, where 0<x≦0.2 and 0<y≦0.4 and a second sublayer of In w Al z Ga 1-w-z N, where 0<w≦0.2 and y≦z<1, wherein the undoped Group III nitride capping layer is directly on a GaN layer; and 
 a p-type Group III nitride layer including aluminum directly on the undoped Group III nitride capping layer and remote from the Group III nitride based light emitting diode active region. 
 
     
     
       17. The light emitting diode of  claim 16 , wherein the first sublayer has a thickness of from about 10 to about 200 Å and the second sublayer has a thickness of from about 10 to about 120 Å. 
     
     
       18. The light emitting diode of  claim 17 , wherein the first sublayer has a thickness of about 80 Å, x=0.1 and y=0.25 and the second sublayer has a thickness of about 30 Å, w=0.05 and z=0.55. 
     
     
       19. A Group III nitride based light emitting diode, comprising:
 an n-type Group III nitride layer; 
 a Group III nitride based light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 an undoped Group III nitride capping layer comprising indium on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the undoped Group III nitride capping layer is directly on a GaN layer; 
 a p-type Group III nitride layer including aluminum directly on the undoped Group III nitride capping layer and remote from the Group III nitride based light emitting diode active region; 
 a second contact on the p-type Group III nitride layer including aluminum; and 
 a p-type Group III nitride layer disposed between the second contact and the p-type Group III nitride layer including aluminum, 
 wherein the p-type Group III nitride layer disposed between the second contact and the p-type Group III nitride layer including aluminum also includes indium. 
 
     
     
       20. A Group III nitride based light emitting diode, comprising:
 an n-type Group III nitride layer; 
 a Group III nitride based light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 an undoped Group III nitride capping layer comprising indium on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the undoped Group III nitride capping layer is directly on a GaN layer; 
 a p-type Group III nitride layer including aluminum directly on the undoped Group III nitride capping layer and remote from the Group III nitride based light emitting diode active region; 
 a first contact on the n-type Group III nitride layer; and 
 a silicon carbide substrate disposed between the first contact and the n-type Group III nitride layer. 
 
     
     
       21. A light emitting diode, comprising:
 an n-type Group III nitride layer, wherein the n-type Group III nitride layer comprises an n-type AlGaN layer on a substrate and an n-type GaN layer on the n-type AlGaN layer; 
 a Group III nitride light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 an undoped quaternary Group III nitride capping layer on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the quaternary Group III nitride capping layer is directly on a binary Group III nitride layer; and 
 a ternary p-type Group III nitride layer directly on the quaternary Group III nitride capping layer and remote from the Group III nitride light emitting diode active region. 
 
     
     
       22. The light emitting diode of  claim 21 , wherein the Group III nitride active region comprises a plurality of InGaN/GaN quantum wells. 
     
     
       23. The light emitting diode of  claim 22 , wherein the ternary p-type Group III nitride layer comprises a p-type AlGaN layer on the undoped quaternary Group III nitride capping layer, and further comprising:
 a p-type GaN layer on the p-type AlGaN layer; and 
 a second contact on the p-type GaN layer. 
 
     
     
       24. The light emitting diode of  claim 23 , wherein the quaternary Group III nitride capping layer comprises:
 a first sublayer of In x Al y Ga 1-x-y N, where 0<x≦0.2 and 0<y≦0.4; and 
 a second sublayer of In w Al z Ga 1-w-z N, where 0<w≦0.2 and y≦z<1. 
 
     
     
       25. The light emitting diode of  claim 24 , wherein the first sublayer has a thickness of from about 10 to about 200 Å and the second sublayer has a thickness of from about 10 to about 120 Å. 
     
     
       26. The light emitting diode of  claim 25 , wherein the first sublayer has a thickness of about 80 Å, x=0.1 and y=0.25 and the second sublayer has a thickness of about 30 Å, w=0.05 and z=0.55. 
     
     
       27. The light emitting diode of  claim 23 , wherein the substrate comprises silicon carbide and further comprising:
 a first contact on the silicon carbide substrate opposite the n-type AlGaN layer. 
 
     
     
       28. The light emitting diode of  claim 21 , wherein the Group III nitride capping layer comprising indium is configured to increase a brightness of light output from the light emitting diode by at least about 15% as compared to a capping layer that does not include indium. 
     
     
       29. The light emitting diode of  claim 21 , wherein the quaternary Group III nitride capping layer comprises InAlGaN, and wherein the binary Group III nitride layer comprises GaN. 
     
     
       30. The light emitting diode of  claim 29 , wherein the binary Group III nitride layer comprises an undoped GaN layer between the light emitting diode active region and the quaternary Group III nitride capping layer. 
     
     
       31. The light emitting diode of  claim 29 , wherein the binary Group III nitride layer comprises a barrier layer of the quantum well structure. 
     
     
       32. A method of fabricating a Group III nitride based light emitting diode, comprising:
 forming an n-type Group III nitride layer; 
 forming a Group III nitride based light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 forming an undoped Group III nitride capping layer comprising indium on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the undoped Group III nitride capping layer comprises a plurality of undoped InAlGaN sublayers, and wherein the undoped Group III nitride capping layer is directly on a GaN layer; and 
 forming a p-type Group III nitride layer including aluminum directly on the Group III nitride capping layer. 
 
     
     
       33. The method of  claim 32 , wherein the undoped Group III nitride capping layer comprising indium is from about 20 Angstroms (Å) to about 320 Å thick. 
     
     
       34. The method of  claim 32 , further comprising:
 forming a second contact on the p-type Group III nitride layer including aluminum; and 
 forming a p-type Group III nitride layer disposed between the second contact and the p-type Group III nitride layer including aluminum. 
 
     
     
       35. The method of  claim 32  wherein the p-type Group III nitride layer including aluminum also includes indium. 
     
     
       36. The method of  claim 32 , wherein the Group III nitride capping layer comprising indium is configured to increase a brightness of light output from the light emitting diode by at least about 15% as compared to a capping layer that does not include indium. 
     
     
       37. A method of fabricating a Group III nitride based light emitting diode, the method comprising:
 forming an n-type Group III nitride layer; 
 forming a Group III nitride based light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 forming an undoped Group III nitride capping layer comprising indium on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the undoped Group III nitride capping layer is directly on a GaN layer; and 
 forming a p-type Group III nitride layer including aluminum directly on the Group III nitride capping layer, 
 wherein forming the undoped Group III nitride capping layer comprises: 
 forming a first sublayer of In x Al y Ga 1-x-y N, where 0<x≦0.2 and 0<y≦0.4; and 
 forming a second sublayer of In w Al z Ga 1-w-z N, where 0<w≦0.2 and y≦z<1. 
 
     
     
       38. The method of  claim 37 , wherein the first sublayer has a thickness of from about 10 to about 200 Å and the second sublayer has a thickness of from about 10 to about 120 Å. 
     
     
       39. The method of  claim 38 , wherein the first sublayer has a thickness of about 80 Å, x=0.1 and y=0.25 and the second sublayer has a thickness of about 30 Å, w=0.05 and z=0.55. 
     
     
       40. A method of fabricating a Group III nitride based light emitting diode, the method comprising:
 forming an n-type Group III nitride layer; 
 forming a Group III nitride based light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 forming an undoped Group III nitride capping layer comprising indium on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the undoped Group III nitride capping layer is directly on a GaN layer; 
 forming a p-type Group III nitride layer including aluminum directly on the Group III nitride capping layer; 
 forming a second contact on the p-type Group III nitride layer including aluminum; and forming a p-type Group III nitride layer disposed between the second contact and the p-type Group III nitride layer including aluminum, 
 wherein the p-type Group III nitride layer disposed between the second contact and the p-type Group III nitride layer including aluminum also includes indium. 
 
     
     
       41. A method of fabricating a Group III nitride based light emitting diode, the method comprising:
 forming an n-type Group III nitride layer on a silicon carbide substrate; 
 forming a Group III nitride based light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 forming an undoped Group III nitride capping layer comprising indium on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the undoped Group III nitride capping layer is directly on a GaN layer; 
 forming a p-type Group III nitride layer including aluminum directly on the Group III nitride capping layer; and 
 forming a first contact on the silicon carbide substrate opposite the n-type Group III nitride layer. 
 
     
     
       42. A method of fabricating a light emitting diode, the method comprising:
 forming an n-type Group III nitride layer; 
 forming a Group III nitride light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 forming an undoped quaternary Group III nitride capping layer on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the quaternary Group III nitride capping layer is directly on a binary Group III nitride layer; and 
 forming a ternary p-type Group III nitride layer directly on the quaternary Group III nitride capping layer, 
 wherein forming the n-type Group II nitride layer comprises: 
 forming an n-type AlGaN layer on a substrate; and 
 forming an n-type GaN layer on the n-type AlGaN layer. 
 
     
     
       43. The method of  claim 42 , wherein forming a Group III nitride active region comprises forming a plurality of InGaN/GaN quantum wells. 
     
     
       44. The method of  claim 42 , wherein forming a p-type Group III nitride layer comprises forming a p-type AlGaN layer on the undoped quaternary Group III nitride capping layer, and further comprising:
 forming a p-type GaN layer on the p-type AlGaN layer; and 
 forming a second contact on the p-type GaN layer. 
 
     
     
       45. The method of  claim 44 , wherein forming the undoped quaternary Group III nitride capping layer comprises:
 forming a first sublayer of In x Al y Ga 1-x-y N, where 0<x ≦0.2 and 0<y≦0.4; and 
 forming a second sublayer of In w Al z Ga 1-w-z N, where 0<w≦0.2 and y≦z<1. 
 
     
     
       46. The method of  claim 45 , wherein the first sublayer has a thickness of from about 10 to about 200 Å and the second sublayer has a thickness of from about 10 to about 120 Å. 
     
     
       47. The method of  claim 46 , wherein the first sublayer has a thickness of about 80 Å, x=0.1 and y=0.25 and the second sublayer has a thickness of about 30 Å, w=0.05 and z=0.55. 
     
     
       48. The method of  claim 44 , wherein the substrate comprises silicon carbide and further comprising:
 forming a first contact on the silicon carbide substrate opposite the n-type AlGaN layer. 
 
     
     
       49. The method of  claim 42 , wherein the Group III nitride capping layer comprising indium is configured to increase a brightness of light output from the light emitting diode by at least about 15% as compared to a capping layer that does not include indium. 
     
     
       50. A light emitting diode, comprising:
 a Group III nitride based superlattice comprising at least two periods of alternating Group III nitride based layers, wherein at least one of the alternating Group III nitride based layers comprises indium; 
 a Group III nitride based light emitting diode active region on the superlattice and comprising at least one quantum well structure comprising indium; 
 an undoped Group III nitride based capping layer comprising indium on the light emitting diode active region; 
 a doped Group III nitride based layer including indium on the capping layer; and 
 a Group III nitride based contact layer including indium on the Group III nitride based layer. 
 
     
     
       51. The light emitting diode of  claim 50 , further comprising:
 an ohmic contact on the Group III nitride based contact layer. 
 
     
     
       52. The light emitting diode of  claim 50 , wherein the light emitting diode comprises a vertical orientation. 
     
     
       53. The light emitting diode of  claim 50 , wherein the undoped Group III nitride based capping layer comprising indium is directly on an undoped GaN layer. 
     
     
       54. A light emitting diode, comprising:
 an n-type Group III nitride layer; 
 a Group III nitride light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure, wherein the light emitting diode active region comprises indium; 
 a gallium nitride based superlattice comprising at least two periods of alternating layers of In x Ga 1-x N and In y Ga 1-y N, where 0≦x<1 and 0≦y<1 and x is not equal to y, between the n-type Group III nitride layer and the light emitting diode active region; 
 an undoped quaternary Group III nitride capping layer on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the quaternary Group III nitride capping layer is directly on a binary Group III nitride layer; and 
 a ternary p-type Group III nitride layer directly on the quaternary Group III nitride capping layer and remote from the Group III nitride light emitting diode region. 
 
     
     
       55. A method of fabricating a light emitting diode, the method comprising:
 forming an n-type Group III nitride layer; 
 forming a Group III nitride light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure, wherein the active region comprises indium; 
 forming an undoped quaternary Group III nitride capping layer on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the quaternary Group III nitride capping layer is directly on a binary Group III nitride layer; and 
 forming a ternary p-type Group III nitride layer directly on the quaternary Group III nitride capping layer, and further comprising: 
 forming a gallium nitride based superlattice comprising at least two periods of alternating layers of In x Ga 1-x N and In y Ga 1-y N, where 0≦x<1 and 0≦y<1 and x is not equal to y, on the n-type Group III nitride layer prior to forming the light emitting diode active region thereon. 
 
     
     
       56. A light emitting diode, comprising:
 an n-type Group III nitride layer; 
 a Group III nitride light emitting diode active region on the n-type Group III nitride layer and comprising at least one quantum well structure; 
 an undoped quaternary Group III nitride capping layer on the light emitting diode active region opposite from the n-type Group III nitride layer, wherein the quaternary Group III nitride capping layer is directly on a binary Group III nitride layer; 
 a ternary p-type Group III nitride layer directly on the quaternary Group III nitride capping layer and remote from the Group III nitride light emitting diode active region; and 
 a binary p-type Group III nitride layer on the ternary p-type Group III nitride layer opposite from the quaternary Group III nitride capping layer.